The investigators state that they are resubmitting this application after careful consideration of the reviewers' thoughtful comments and suggestions and extensive revision. Specifically, they have joined forces with the team of Dr. Stanley Azen at the University of Southern California Statistical Data Coordinating Center. The South Bay Heart Watch (SBHW) is a population-based study of high-risk subjects with baseline risk factor measurements and coronary calcium determinations by EBCT conducted in 1994. This study has shown a modest relation between coronary calcium and the incidence of future cardiovascular events. In the proposed research, the investigators will use the SBHW cohort and NHLBI reading center as well as Dr. Azen's data coordinating center to examine whether baseline risk factors, ethnic group and indices of calcium metabolism are associated with change in coronary calcium quantity over four to five years. They will perform EBCT scans in 1,000 surviving members of the cohort and will perform repeat measurements of left ventricular hypertrophy, plasma lipids, blood pressure, homocysteine, fibrinogen, para-thyroid hormone and vitamin D levels. They will examine the independent relationships between risk factors from the 1994 baseline evaluation and the change in coronary calcium score as determined by EBCT. Logistic regression, which is not dependent on normality of the independent variables, will be used to examine the relation of annualized change in coronary calcium with the incidence of events. The investigators state that this study will have important implications regarding the significance of risk factors and progression of sub-clinical diseases measured by changes in calcium, as well as the relation of calcium change to incident events. They also state that important information regarding the effect of risk factors on sub-clinical disease progression and the transition of disease to cardiovascular events will be obtained.